Melanoma is a very aggressive cancer that metastasizes early in disease progression and is highly resistant to present therapeutics. These characteristics of melanoma may be innate rather than acquired, since the source of this tumor, the melanocyte, has a high capacity to migrate and survive for relatively long periods. This parallelism between melanocytes and melanoma is most likely due to shared molecular pathways between both cell types. PAX3 is a transcription factor necessary for normal melanocyte development, growth, and migration. Due to these developmental roles, it is not surprising that we have found PAX3 also is aberrantly expressed in melanoma and promotes tumor growth and progression. PAX3 is a significant driver of melanoma since it actively promotes the expression of a number of genes involved in tumor growth, survival and migration. However, the factors that regulates and works with PAX3, and how can this knowledge be translated to new and effective therapeutic opportunities for melanoma patients, is unknown. Therefore, we hypothesize that maintained expression and function of the PAX3 protein is a key driver of melanoma, and disruption of PAX3 co-factors and upstream regulators will be deleterious to melanoma progression and survival. The major objectives of this application are to determine the mechanism of PAX3 maintenance of expression and function in melanoma, identify molecular members of the pathways that regulate PAX3, determine if these molecules will be good targets for melanoma therapy, and see if these candidates play a role in tumor initiation and/or progression. Our long-term goal is to identify small molecule therapeutics that will provide alternate or combination therapy in melanoma. We have already identified some of the factors that drive PAX3 gene expression through conserved enhancer elements, as well as proteins that directly bind to and enhance PAX3 function. Our general strategy is to determine if these molecules do indeed promote PAX3 function and melanoma progression on a molecular level and within cellulo models, and within relevant in vivo mouse melanoma models. This study is significant and impactful since it will uncover the mechanism of PAX3 maintenance and function in melanoma, identify co-factors, provide several new therapeutic options, and utilize small molecule inhibitors in a pre-clinical murine model of melanoma. This work is innovative because it will identify novel molecular pathways in melanoma and test new uses for small-molecule inhibitors for melanoma either singularly or in combination. The completion of this work will reveal novel components of molecular pathways driving melanoma. Elucidation of these pathways will provide translational impact through the identification of unique therapeutic targets for a disease with few treatment options.